Herbicidal N-aryltetrahydrophthalimide derivatives

ABSTRACT

N-aryltetrahydrophthalimide derivatives and intermediates therefor of the general formula I ##STR1## where A is O 2  N--, H 2  N-- or ##STR2## corresponding to compounds Ia, Ib and Ic, R 1  is hydrogen, fluorine or chlorine, 
     R 2  is hydrogen or cyano, 
     R 3  is C 1  -C 6  -alkyl, C 2  -C 6  -alkenyl or C 2  -C 6  -alkynyl, which each may be substituted by halogen or C 1  -C 4  -alkoxy, or is C 1  -C 3  -alkyl, which may be substituted by C 3  -C 8  -alkenyl, C 3  -C 8  -alkynyloxycarbonyl or C 2  -C 10  -alkoxycarbonyl which may be substituted in the alkoxy moiety by C 1  -C 4  -alkoxy, halogen or phenyl, 
     and herbicides which contain compounds of the formula Ic.

The present invention relates to novel N-aryltetrahydrophthalimidederivatives and intermediates therefor of the general formula I ##STR3##where A is O₂ N--, H₂ N-- or ##STR4## corresponding to compounds Ia, Iband Ic, R¹ is hydrogen, fluorine or chlorine,

R² is hydrogen or cyano,

R³ is C₁ -C₆ -alkyl, C₂ -C₆ -alkenyl or C₂ -C₆ -alkynyl, which each maybe substituted by halogen or C₁ -C₄ -alkoxy, or is C₁ -C₃ -alkyl, whichmay be substituted by C₃ -C₈ -alkenyl, C₃ -C₈ -alkynyloxycarbonyl or C₂-C₁₀ -alkoxycarbonyl which may be substituted in the alkoxy moiety by C₁-C₄ -alkoxy, halogen or phenyl.

The present invention also relates to the use of theN-aryltetrahydrophthalimide derivatives Ic as herbicides and toherbicides which contain compounds of the formula Ic.

GB-A-2,150,929 discloses N-aryltetrahydrophthalimides of type I'##STR5## where R^(1') is hydrogen, halogen or pseudohalogen,

R^(2') and R^(3') are each independently hydrogen, alkyl, alkaryl,araryl, aryl, alkoxyalkyl, alkoxycarbonylalkyl or haloalkyl.

These compounds have been recommended for use as herbicides, but inparticular at low application rates they leave something to be desired.

It is an object of the present invention to develop newN-aryltetrahydrophthalimide derivatives Ic of improved herbicidal actionfor the same or a reduced application rate.

We have found that this object is achieved with a novelN-aryltetrahydrophthalimide derivative Ic defined above. We have alsofound that a compound Ic is highly suitable for use as a herbicide.

Characteristic of the general herbicidal action of compounds Ic is the3,4,5,6-tetrahydrophthalimide group.

The oxime ether moiety ##STR6## has a favorable effect in respect ofenhanced action and selectivity of the herbicide.

Compounds Ia are obtainable by the following methods:

(a) For the case where R² is hydrogen: The nitrobenzene oxime compoundsof the formula Ia can be prepared in similar manner to known processesby reacting the nitroformyl compound IIa either with hydroxylaminehydrochloride in the presence of acid-binding agents to give an oximeIIa' and subsequently reacting the latter with a compound R³ -Br, ordirectly with an O-substituted hydroxylamine H₂ NO-R³ or a salt thereofin the presence or absence of an acid-binding agent. ##STR7##

(b) For the case where R² is cyano: The nitrobenzene oxime compounds Iaare obtained by reacting m-nitrobenzyl cyanide IIa"' with an alkylnitrite R⁴ ONO, where R⁴ is C₁ -C₈ -alkyl, in the presence of a sodiumalcoholate at from 0° C. to room temperature to give the sodium salt ofthe oximinonitrile of the formula IIa^(IV) and subsequently reacting thelatter with a compound R³ -Br at room temperature in an aprotic dipolarsolvent such as acetonitrile. In one version, the nitro compound IIa^(V)is obtained by reacting an o-chlorobenzyl cyanide IIa^(VI) with an alkylnitrite R⁴ ONO in the abovementioned manner to give the sodium salt ofthe oximinonitrile IIa^(VI), then reacting the latter with a compound R³-Br in an aprotic dipolar solvent and finally reacting the product withnitrating acid at from -10° to +50° C., preferably at from 0° to 25° C.##STR8##

Compounds Ib are obtainable by the following methods:

The aniline oxime derivative Ib is prepared in a conventional manner byreducing the nitro compound Ia, either by reducing with the salt ofdivalent tin or iron in an aqueous acidic alcoholic medium, for exampleHCl/water/ethanol, or by partial catalytic hydrogenation by means of anoble metal catalyst, for example platinum or palladium, at from 0° to50° C. ##STR9##

Compounds Ic are obtainable by the following methods:

The N-aryltetrahydrophthalimide Ic is obtainable from3,4,5,6-tetrahydrophthalic anhydride and an aniline oxime derivative inthe presence or absence of a solvent at from 60° to 200° C. Suitablesolvents are lower carboxylic acids, such as glacial acetic acid orpropionic acid or aprotic solvents. On working in an aprotic solvent, itis advisable to employ a water separator to remove the water of reactionazeotropically. ##STR10## Of compounds Ic, preference is given to thosewhere R¹ is hydrogen or chlorine. R² is preferably hydrogen.

Preferred radicals R³ are

C₁ -C₄ -alkyl, in particular methyl, ethyl or n-propyl,

C₂ -C₄ -alkenyl, in particular vinyl or allyl,

C₂ -C₄ -alkynyl, in particular ethynyl,

C₁ -C₄ -haloalkyl, in particular trifluoromethyl or trichloromethyl,

C₁ -C₂ -alkyl, which is substituted by C₂ -C₉ -alkoxycarbonyl, inparticular methoxycarbonylmethyl, ethoxycarbonylmethyl,methoxycarbonyleth-1-yl, ethoxycarbonyleth-1-yl,n-propoxycarbonyleth-1-yl, n-butoxycarbonylmethyl,n-hexoxycarbonylmethyl, n-butoxycarbonyleth-1-yl,n-pentoxycarbonyleth-1-yl, n-octyloxycarbonyleth-1-yl or(2-ethyl-n-hexyloxy)carbonyleth-1-yl,

C₁ -C₂ -alkyl which is substituted by C₃ -C₆ -alkenyloxycarbonyl, inparticular allyloxycarbonylmethyl or allyloxycarbonyleth-1-yl,

C₁ -C₂ -alkyl which is substituted by C₃ -C₆ -alkynyloxycarbonyl, inparticular ethynyloxycarbonyleth-1-yl,

C₁ -C₂ -alkyl which is substituted by C₂ -C₆ -alkoxycarbonyl which issubstituted in the alkoxy moiety by C₁ -C₄ -alkoxy, in particularmethoxymethoxycarbonylmethyl, methoxymethoxycarbonyleth-1-yl,ethoxymethoxycarbonylethyl and ethoxymethoxycarbonyleth-1-yl,

C₁ -C₂ -alkyl which is substituted by C₂ -C₆ -alkoxycarbonyl which issubstituted in the alkoxy moiety by phenyl, in particularbenzyloxycarbonylmethyl and benzyloxycarbonyleth-1-yl.

When R² is hydrogen, R³ is particularly preferably methyl, ethyl,n-propyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, ormethoxycarbonyleth-, ethoxycarbonyleth-, n-propyloxycarbonyleth- orallyloxycarbonyleth-1-yl. When R² is cyano, R³ is particularlypreferably methyl, allyl, methoxycarbonylmethyl, ethoxycarbonylmethyl ormethoxycarbonyleth-1-yl.

Examples of suitable compounds are 3,4,5,6-tetrahydrophthalimides havingthe following substituents on the imide nitrogen:

3-(methoxyiminomethyl)-4-chlorophenyl

3-(ethoxyiminomethyl)-4-chlorophenyl

3-(n-propyliminomethyl)-4-chlorophenyl

3-(allyliminomethyl)-4-chlorophenyl

3-(methoxyethoxyiminomethyl)-4-chlorophenyl

3-(propargyloxyiminomethyl)-4-chlorophenyl

3-(methoxycarbonylmethoxyiminomethyl)-4-chlorophenyl

3-(ethoxycarbonylmethoxyiminomethyl)-4-chlorophenyl

3-(n-propoxycarbonylmethoxyiminomethyl)-4-chlorophenyl

3-(n-butoxycarbonylmethoxyiminomethyl)-4-chlorophenyl

3-(tert.-butoxycarbonylmethoxyiminomethyl)-4-chlorophenyl

3-(n-hexoxycarbonylmethoxyiminomethyl)-4-chlorophenyl

3-(methoxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(ethoxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(n-propoxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(isopropoxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(n-butoxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(allyloxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(isobutoxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(tert.-butoxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(n-pentoxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(n-octyloxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(propargyloxycarbonylmethylmethoxyiminomethyl)-4-chlorophenyl

3-(methoxycarbonylethylmethoxyiminomethyl)-4-chlorophenyl

3-(ethoxycarbonylethylmethoxyiminomethyl)-4-chlorophenyl

3-(methoxycarbonyldimethylmethoxyiminomethyl)-4-chlorophenyl

3-(ethoxycarbonyldimethylmethoxyiminomethyl)-4-chlorophenyl

5-(methoxyiminomethyl)-2,4-dichlorophenyl

5-(ethoxyiminomethyl)-2,4-dichlorophenyl

5-(n-propoxyiminomethyl)-2,4-dichlorophenyl

5-(allyloxyiminomethyl)-2,4-dichlorophenyl

5-(ethoxycarbonylmethoxyiminomethyl)-2,4-dichlorophenyl

5-(n-butoxycarbonylmethoxyiminomethyl)-2,4-dichlorophenyl

5-(n-propoxycarbonylmethylmethoxyiminomethyl)-2,4-dichlorophenyl

5-(ethoxycarbonylmethoxyiminomethyl)-4-chloro-2-fluorophenyl

5-(n-butoxycarbonylmethoxyiminomethyl)-4-chloro-2-fluorophenyl

5-(n-propoxycarbonylmethylmethoxyiminomethyl)-4-chloro-2-fluorophenyl

3-(methoxyiminoacetonitrile)-4-chlorophenyl

3-(ethoxyiminoacetonitrile)-4-chlorophenyl

3-(allyloxyiminoacetonitrile)-4-chlorophenyl

3-(methoxycarbonylmethoxyiminoacetonitrile)-4-chlorophenyl

3-(ethoxycarbonylmethoxyiminoacetonitrile)-4-chlorophenyl

3-(n-propoxycarbonylmethoxyiminoacetonitrile)-4-chlorophenyl

3-(methoxycarbonylmethylmethoxyiminoacetonitrile)-4-chlorophenyl

3-(ethoxycarbonylmethylmethoxyiminoacetonitrile)-4-chlorophenyl

3-(n-propoxycarbonylmethyl(methoxyiminoacetonitrile)-4-chlorophenyl

5-(methoxyiminoacetonitrile)-2,4-dichlorophenyl

5-(allyloxyiminoacetonitrile)-2,4-dichlorophenyl

5-(methoxycarbonylmethoxyiminoacetonitrile)-2,4-dichlorophenyl

5-(ethoxycarbonylmethoxyiminoacetonitrile)-2,4-dichlorophenyl

5-(methoxycarbonylmethylmethoxyiminoacetonitrile)-2,4-dichlorophenyl

5-(ethoxycarbonylmethylmethoxyiminoacetonitrile)-2,4-dichlorophenyl

5-(n-propoxycarbonylmethylmethoxyiminoacetonitrile)-2,4-dichlorophenyl

The N-aryltetrahydrophthalimides Ic, or herbicidal agents containingthem, may be applied for instance in the form of directly sprayablesolutions, powders, suspensions (including high-percentage aqueous, oilyor other suspensions), dispersions, emulsions, oil dispersions, pastes,dusts, broadcasting agents or granules by spraying, atomizing, dusting,broadcasting or watering. The forms of application depend entirely onthe purpose for which the agents are being used, but they must ensure asfine a distribution of the active ingredients according to the inventionas possible.

For the preparation of solutions, emulsions, pastes and oil dispersionsto be sprayed direct, mineral oil fractions of medium to high boilingpoint, such as kerosene or diesel oil, further coal-tar oils, and oilsof vegetable or animal origin, aliphatic, cyclic and aromatichydrocarbons such as benzene, toluene, xylene, and paraffin,tetrahydrocarbons such as methanol, ethanol, propanol, butanol,chloroform, carbon tetrachloride, cyclohexanol, cyclohexanone,chlorobenzene, isophorone, etc., and strongly polar solvents such asdimethylformamide, dimethyl sulfoxide, N-methyl-pyrrolidone, water, etc.are suitable.

Aqueous formulations may be prepared from emulsion concentrates, pastes,oil dispersions or wettable powders by adding water. To prepareemulsions, pastes and oil dispersions the ingredients as such ordissolved in an oil or solvent may be homogenized in water by means ofwetting or dispersing agents, adherents or emulsifiers. Concentrateswhich are suitable for dilution with water may be prepared from activeingredient, wetting agent, adherent, emulsifying or dispersing agent andpossibly solvent or oil.

Examples of surfactants are: alkali metal, alkaline earth metal andammonium salts of ligninsulfonic acid, naphthalenesulfonic acids,phenol-sulfonic acids, alkylaryl sulfonates, alkyl sulfates, and alkylsulfonates, alkali metal and alkaline earth metal salts ofdibutylnaphthalenesulfonic acid, lauryl ether sulfate, fatty alcoholsulfates, alkali metal and alkaline earth metal salts of fatty acids,salts of sulfated hexadecanols, heptadecanols and octadecanols, salts ofsulfated fatty alcohol glycol ethers, condensation products ofsulfonated naphthalene and naphthalene derivatives with formaldehyde,condensation products of naphthalene or naphthalenesulfonic acids withphenol or formaldehyde, polyoxyethylene octylphenol ethers, ethoxylatedisooctylphenol, ethoxylated octylphenol and ethoxylated nonylphenol,alkylphenol polyglycol ethers, tributylphenyl polyglycol ethers,alkylaryl polyether alcohols, isotridecyl alcohol, fatty alcoholethylene oxide condensates, ethoxylated castor oil, polyoxyethylenealkyl ethers, ethoxylated polyoxypropylene, lauryl alcohol polyglycolether acetal, sorbitol esters, lignin, sulfite waste liquors and methylcellulose.

Powders, dusts and broadcasting agents may be prepared by mixing orgrinding the active ingredients with a solid carrier.

Granules, e.g., coated, impregnated or homogeneous granules, may beprepared by bonding the active ingredients to solid carriers. Examplesof solid carriers are mineral earths such as silicic acid, silica gels,silicates, talc, kaolin, attapulgus clay, limestone, lime, chalk, bole,loess, clay, dolomite, diatomaceous earth, calcium sulfate, magnesiumsulfate, magnesium oxide, ground plastics, fertilizers such as ammoniumsulfate, ammonium phosphate, ammonium nitrate and ureas, and vegetableproducts such as grain flours, bark meal, wood meal and nutshell meal,cellulosic powders, etc.

The formulations contain from 0.1 to 95, and preferably from 0.5 to 90,% by weight of active ingredient.

The active ingredients, or agents containing them, may be applied pre-or postemergence. If certain crop plants tolerate the active ingredientsless well, application techniques may be used in which the herbicidalagents are sprayed from suitable equipment in such a manner that theleaves of sensitive crop plants are if possible not touched, and theagents reach the soil or the unwanted plants growing beneath the cropplants (post-directed, lay-by treatment).

The amount of active ingredient applied depends on the time of year, theplants to be combated and their growth stage, and varies from 0.01 to5.0, and preferably from 0.03 to 0.5, kg/ha.

In view of the number of weeds that can be combated, the tolerance ofthe active ingredients by crop plants, and the desired influence ontheir growth, and in view of the numerous application methods possible,the compounds according to the invention may--depending on theirsubstitution pattern--be used in a large number of crop plants.

The following crops may be mentioned by way of example:

    ______________________________________                                        Botanical name         Common name                                            ______________________________________                                        Allium cepa            onions                                                 Ananas comosus         pineapples                                             Arachis hypogaea       peanuts                                                                       (groundnuts)                                           Asparagus officinalis  asparagus                                              Avena sativa           oats                                                   Beta vulgaris spp. altissima                                                                         sugarbeets                                             Beta vulgaris spp. rapa                                                                              fodder beets                                           Beta vulgaris spp. esculenta                                                                         table beets, red                                                              beets                                                  Brassica napus var. napus                                                                            rapeseed                                               Brassica napus var. napobrassica                                                                     swedes                                                 Brassica napus var. rapa                                                                             turnips                                                Brassica rapa var. silvestris                                                 Camellia sinensis      tea plants                                             Carthamus tinctorius   safflower                                              Carya illinoinensis    pecan trees                                            Citrus limon           lemons                                                 Citrus maxima          grapefruits                                            Citrus reticulata      mandarins                                              Citrus sinensis        orange trees                                           Coffea arabica (Coffea canephora,                                                                    coffee plants                                          Coffea liberica)                                                              Cucumis melo           melons                                                 Cucumis sativus        cucumbers                                              Cynodon dactylon       Bermudagrass                                           Daucus carota          carrots                                                Elais guineensis       oil palms                                              Fragaria vesca         strawberries                                           Glycine max            soybeans                                               Gossypium hirsutum (Gossypium arboreum                                                               cotton                                                 Gossypium herbaceum, Gossypium vitifolium)                                    Helianthus annuus      sunflowers                                             Helianthus tuberosus   Jerusalem artichoke                                    Hevea brasiliensis     rubber plants                                          Hordeum vulgare        barley                                                 Humulus lupulus        hops                                                   Ipomoea batatas        sweet potatoes                                         Juglans regia          walnut trees                                           Lactuca sativa         lettuce                                                Lens culinaris         lentils                                                Linum usitatissimum    flax                                                   Lycopersicon lycopersicum                                                                            tomatoes                                               Malus spp.             apple trees                                            Manihot esculenta      cassava                                                Medicago sativa        alfalfa (lucerne)                                      Mentha piperita        peppermint                                             Musa spp.              banana plants                                          Nicothiana tabacum (N. rustica)                                                                      tobacco                                                Olea europaea          olive trees                                            Oryza sativa           rice                                                   Phaseolus lunatus      limabeans                                              Phaseolus mungo        mungbeans                                              Phaseolus vulgaris     snapbeans,                                                                    greenbeans                                                                    dry beans                                              Pennisetum glaucum     pearl millet                                           Petroselinum crispum spp. tuberosum                                                                  parsley                                                Picea abies            Norway spruce                                          Abies alba             fir trees                                              Pinus spp.             pine trees                                             Pisum sativum          English peas                                           Prunus avium           cherry trees                                           Prunus domestica       plum trees                                             Prunus dulcis          almond trees                                           Prunus persica         peach trees                                            Pyrus communis         pear trees                                             Ribes sylvestre        redcurrants                                            Ribes uva-crispa gooseberries                                                 Ricinus communis       castor-oil plants                                      Saccharum officinarum  sugar cane                                             Secale cereale         rye                                                    Sesamum indicum        sesame                                                 Solanum tuberosum      lrish potatoes                                         Sorghum bicolor (s. vulgare)                                                                         sorghum                                                Sorghum dochna         sorgo                                                  Spinacia oleracea      spinach                                                Theobroma cacao        cacao plants                                           Trifolium pratense     red clover                                             Triticum aestivum      wheat                                                  Vaccinium corymbosum   blueberries                                            Vaccinium vitis-idaea  cranberries                                            Vicia faba             tick beans                                             Vigna sinensis (V. unguiculata)                                                                      cow peas                                               Vitis vinifera         grapes                                                 Zea mays               lndian corn,                                                                  sweet corn,                                                                   maize                                                  ______________________________________                                    

To increase the spectrum of action and to achieve synergistic effects,the N-aryltetrahydrophthalimide derivatives of the general formula I maybe mixed and applied together with numerous representatives of otherherbicidal or growth-regulating active ingredient groups. Examples ofsuitable mixture components are diazines, 4H-3,1-benzoxazinederivatives, benzothiadiazinones, 2,6-dinitroanilines,N-phenylcarbamates, thiolcarbamates, halocarboxylic acids, triazines,amides, other ureas, diphenyl ethers, triazinones, uracils, benzofuranderivatives, cyclohexane-1,3-dione derivatives, etc.

The novel N-aryltetrahydrophthalimide derivatives Ic may be applied ontheir own or together with other herbicides and/or crop protectionagents. Examples of these are agents for combating pests orphytopathogenic fungi or bacteria. It is also possible to preparemixtures with mineral salt solutions and with non-phytotoxic oils andoil concentrates.

EXAMPLES

Manufacture of N-substituted aryltetrahydrophthalimide derivatives Ic

EXAMPLES 1 TO 4

At 20° C., 230 mmoles of O-methylenehydroxylamine hydrochloride wasadded to a solution of 150 mmoles of a 2-chloro-5-nitrobenzaldehydederivative in 150 ml of methylene chloride. Subsequently, 240 mmoles oftriethylamine in 20 ml of methylene chloride was dripped in. The mixturewas then stirred for 15 hours at room temperature and worked up in theusual manner.

A solution of 92 mmoles of the product in 400 ml of ethyl acetate washydrogenated in the presence of 2 g of 10% Pd/carbon (10 wt%) at 17° to20° C. while stirring, and worked up in the usual manner.

100 mmoles of the product obtained in this manner and 105 mmoles of3,4,5,6-tetrahydrophthalic anhydride were heated for 8 hours in 180 mlof glacial acetic acid and worked up in the usual manner.

The results are given in Table 1.

                  TABLE 1                                                         ______________________________________                                        Compound                                                                      No.        R.sup.1                                                                             R.sup.2   R.sup.3                                                                             Mp. [ C.]                                    ______________________________________                                        Compounds Ia                                                                  (A = O.sub.2 N)                                                               1a         H     H         CH.sub.3                                                                            98-99                                        2a         H     H         C.sub.2 H.sub.5                                                                     56-57                                        3a         H     H         n-C.sub.3 H.sub.7                                                                   37-38                                        4a         Cl    H         CH.sub.3                                                                            68-70                                        Compounds Ib                                                                  (A = H.sub.2 N)                                                               1b         H     H         CH.sub.3                                                                            47-49                                        2b         H     H         C.sub.2 H.sub.5                                                                     48-54                                        3b         H     H         n-C.sub.3 H.sub.7                                                                   oil                                          4b         Cl    H         CH.sub.3                                                                            viscous mass                                 Compounds Ic                                                                   ##STR11##                                                                    1c         H     H         CH.sub.3                                                                            139-41                                       2c         H     H         C.sub.2 H.sub.5                                                                     97-98                                        3c         H     H         n-C.sub.3 H.sub.7                                                                   86-87                                        4c         Cl    H         CH.sub.3                                                                            143-145                                      ______________________________________                                    

EXAMPLES 5 TO 21

At room temperature and while stirring, 200 mmoles of powdered potassiumcarbonate was introduced in 4 portions into a solution of 100 mmoles ofa 2-chloro-5-nitrobenzaldehydeoxime derivative and 110 mmoles ofbromocarboxylic acid ester in 140 ml of dry dimethylformamide, and themixture was stirred for 15 hours at room temperature. The mixture wasthen stirred into 600 ml of cold water and subjected to suctionfiltration, and the residue was worked up in the usual manner.

65 ml of concentrated hydrochloric acid was added to a solution of theproduct in 270 ml of ethanol, and 490 mmoles of tin(II) chloridedihydrate was introduced over a period of 30 minutes while stirring; themixture was subsequently stirred for 1 hour at 60° C. The ethanol wasevaporated under reduced pressure, and the residue was introduced into amixture of 155 ml of 50 wt% aqueous NaOH and 400 ml of ice water in sucha manner that the temperature did not exceed +5° C. The mixture wasworked up in the usual manner.

79 mmoles of this product and 87 mmoles of 3,4,5,6-tetrahydrophthalicanhydride were stirred in 150 ml of glacial acetic acid for 1 hour at50° C. and refluxed for 7 hours. After the mixture had cooled, it wasworked up in the usual manner.

The results are shown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________    Compound                                                                      No.    R.sup.1                                                                          R.sup.2                                                                          R.sup.3             Mp. [°C.]                             __________________________________________________________________________    Compounds Ia                                                                  (A = O.sub.2 N)                                                                5a    H  H  CH.sub.2 CO.sub.2 CH.sub.3                                                                        106-107                                       6a    H  H  CH.sub.2 CO.sub.2 C.sub.2 H.sub.5                                                                 71-72                                         7a    H  H  CH(CH.sub.3)CO.sub.2 CH.sub.3                                                                     89-90                                         8a    H  H  CH(CH.sub.3)CO.sub.2 C.sub.2 H.sub.5                                                              65-67                                         9a    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.3 H.sub.7                                                             73-75                                        10a    H  H  CH(CH.sub.3)CO.sub.2 CH.sub.2CHCH.sub.2                                                           73-74                                        11a    H  H  CH.sub.2CO.sub.2n-C.sub.4 H.sub.9                                                                 oil                                          12a    H  H  CH.sub.2CO.sub.2n-C.sub.6 H.sub.13                                                                64-65                                        13a    H  H  CH.sub.2CO.sub.2CH.sub.2CHCH.sub.2                                                                65-67                                        14a    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.4 H.sub.9                                                             oil                                          15a    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.5 H.sub.11                                                            oil                                          16a    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.8 H.sub.17                                                            oil                                          17a    H  H  CH(CH.sub.3)CO.sub.2CH.sub.2 CH(C.sub.2 H.sub.5)n-C.sub.4                     H.sub.9             oil                                          18a    H  H  CH(CH.sub.3)CO.sub.2CCH                                                                           110-111                                      19a    H  H                                                                                 ##STR12##          68-72                                        20a    H  H  CH(CH.sub.3)CO.sub.2 (CH.sub.3)OCH.sub.3                                                          40-45                                        21a    H  H  CH(CH.sub.3)CO.sub.2 (CH.sub.2).sub.2 OC.sub.2 H.sub.5                                            61-62                                        Compounds Ib                                                                  (A = H.sub.2 N)                                                                5b    H  H  CH.sub.2 CO.sub.2 CH.sub.3                                                                        oil                                           6b    H  H  CH.sub.2 CO.sub.2 C.sub.2 H.sub.5                                                                 34-36                                         7b    H  H  CH(CH.sub.3)CO.sub.2 CH.sub.3                                                                     oil                                           8b    H  H  CH(CH.sub.3)CO.sub.2 C.sub.2 H.sub.5                                                              viscous mass                                  9b    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.3 H.sub.7                                                             viscous mass                                 10b    H  H  CH(CH.sub.3)CO.sub.2 CH.sub.2CHCH.sub.2                                                           viscous mass                                 11b    H  H  CH.sub.2CO.sub.2n-C.sub.4 H.sub.9                                                                 oil                                          12b    H  H  CH.sub.2CO.sub.2n-C.sub.6 H.sub. 13                                                               oil                                          13b    H  H  CH.sub.2CO.sub.2CH.sub.2CHCH.sub.2                                                                oil                                          14b    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.4 H.sub.9                                                             oil                                          15b    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.5 H.sub.11                                                            oil                                          16b    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.8 H.sub.17                                                            oil                                          17b    H  H  CH(CH.sub.3)CO.sub.2CH.sub.2 CH(C.sub.2 H.sub.5)n-C.sub.4                     H.sub.9             oil                                          18b    H  H  CH(CH.sub.3)CO.sub.2CCH                                                                           oil                                          19b    H  H                                                                                 ##STR13##          oil                                          20b    H  H  CH(CH.sub.3)CO.sub.2 (CH.sub.2).sub.2 OCH.sub.3                                                   oil                                          21b    H  H  CH(CH.sub.3)CO.sub.2 (CH.sub.2).sub.2 OC.sub.2 H.sub.5                                            oil                                          Compounds Ic                                                                   ##STR14##                                                                     5c    H  H  CH.sub.2 CO.sub.2 CH.sub.3                                                                        oil                                           6c    H  H  CH.sub.2 CO.sub.2 C.sub.2 H.sub.5                                                                 116-117                                       7c    H  H  CH(CH.sub.3 )CO.sub.2 CH.sub.3                                                                    viscous mass                                  8c    H  H  CH(CH.sub.3)CO.sub.2 C.sub.2 H.sub.5                                                              85-87                                         9c    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.3 H.sub.7                                                             viscous mass                                 10c    H  H  CH(CH.sub.3)CO.sub.2 CH.sub.2CHCH.sub.2                                                           viscous mass                                 11c    H  H  CH.sub.2CO.sub.2n-C.sub.4 H.sub.9                                                                 91-92                                        12c    H  H  CH.sub.2CO.sub.2n-C.sub.6 H.sub.13                                                                64-66                                        13c    H  H  CH.sub.2CO.sub.2CH.sub.2CHCH.sub.2                                                                83-86                                        14c    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.4 H.sub.9                                                             oil                                          15c    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.5 H.sub.11                                                            oil                                          16c    H  H  CH(CH.sub.3)CO.sub.2n-C.sub.8 H.sub.17                                                            oil                                          17c    H  H  CH(CH.sub.3)CO.sub.2CH.sub.2 CH(C.sub.2 H.sub.5)n-C.sub.4                     H.sub.9             oil                                          18c    H  H  CH(CH.sub.3)CO.sub.2CCH                                                                           oil                                          19c    H  H                                                                                 ##STR15##          oil                                          20c    H  H  CH(CH.sub.3)CO.sub.2 (CH.sub.2).sub.2 OCH.sub.3                                                   oil                                          21c    H  H  CH(CH.sub.3)CO.sub.2 (CH.sub.2).sub.2 OC.sub.2 H.sub.5                                            oil                                          __________________________________________________________________________

EXAMPLES 22 TO 29

560 mmoles of a 2-chlorobenzylcyanide derivative was introduced into asolution of 560 mmoles of 30% strength sodium methylate in 200 ml ofethanol. At +10° C. and while stirring, 280 mmoles of neopentyl glycoldinitrite was dripped in over a period of 30 minutes, and stirring wascontinued for a further 30 minutes at 25° C. at +5° C., 200 ml of methyltert-butyl ether was dripped in and the mixture was then worked up inthe usual manner.

At room temperature, 160 mmoles of a bromide R³ -Br was dripped into asolution of 150 mmoles of this sodium salt in 150 ml of drydimethyl-formamide. After the mixture has been stirred for 24 hours itwas worked up in the usual manner.

At +5° C., 110 mmoles of this reaction mixture was dripped, whilestirring, into a mixture of 12 ml of 100% strength HNO₃ (d=1.51) and 100ml of concentrated H₂ SO₄ ; the mixture was stirred for 2 hours at +5°C. The reaction mixture was poured onto 500 g of ice and worked up inthe usual manner.

Similarly to Examples 5 to 10, the corresponding aniline was obtained asan oil from 41 mmoles of this nitro compound in 120 ml of methanol and26 ml of concentrated hydrochloric acid by reduction with 36 g oftin(II) chloride dihydrate.

32 mmoles of the aniline obtained and 35 mmoles of3,4,5,6-tetrahydrophthalic anhydride in 100 ml of glacial acetic acidwere reacted similarly to Examples 5 to 10. The compound obtained waspurified by chromatography using silica gel and a 9:1 mixture of tolueneand ethyl acetate.

The results are given in Table 3.

                  TABLE 3                                                         ______________________________________                                        Compound                                                                      No.      R.sup.1                                                                              R.sup.2 R.sup.3     Mp. [°C.]                          ______________________________________                                        Compounds Ia                                                                  (A = O.sub.2 N)                                                               22a      H      CN      CH.sub.2CHCH.sub.2                                                                        73-75                                     23a      H      CN      CH.sub.2CO.sub.2 CH.sub.3                                                                 105-107                                   24a      H      CN      CH.sub.2CO.sub.2 C.sub.2 H.sub.5                                                          104-105                                   25a      H      CN      CH(CH.sub.3)CO.sub.2 CH.sub.3                                                             oil                                       26a      Cl     CN      CH.sub.3    78-81                                     27a      Cl     CN      CH.sub.2CO.sub.2 CH.sub.3                                                                 107-109                                   28a      Cl     CN      CH.sub.2CO.sub.2 C.sub.2 H.sub.5                                                          109                                       29a      Cl     CN      CH(CH.sub.3)CO.sub.2 CH.sub.3                                                             111-113                                   Compounds Ib                                                                  (A = H.sub.2 N)                                                               22b      H      CN      CH.sub.2CHCH.sub.2                                                                        oil                                       23b      H      CN      CH.sub.2CO.sub.2 CH.sub.3                                                                 oil                                       24b      H      CN      CH.sub.2CO.sub.2 C.sub.2 H.sub.5                                                          oil                                       25b      H      CN      CH(CH.sub.3)CO.sub.2 CH.sub.3                                                             viscous mass                              26b      Cl     CN      CH.sub.3    88-91                                     27b      Cl     CN      CH.sub.2CO.sub.2 CH.sub. 3                                                                95-98                                     28b      Cl     CN      CH.sub.2CO.sub.2 C.sub.2 H.sub.5                                                          79-82                                     29b      Cl     CN      CH(CH.sub.3)CO.sub.2 CH.sub.3                                                             oil                                       Compounds Ic                                                                   ##STR16##                                                                    22c      H      CN      CH.sub.2CHCH.sub.2                                                                        oil                                       23c      H      CN      CH.sub.2CO.sub.2 CH.sub.3                                                                 viscous mass                              24c      H      CN      CH.sub.2CO.sub.2 C.sub.2 H.sub.5                                                          viscous mass                              25c      H      CN      CH(CH.sub.3)CO.sub.2 CH.sub.3                                                             viscous mass                              26c      Cl     CN      CH.sub.3    oil                                       27c      Cl     CN      CH.sub.2CO.sub.2 CH.sub.3                                                                 108-110                                   28c      Cl     CN      CH.sub.2CO.sub.2 C.sub.2 H.sub.5                                                          oil                                       29c      Cl     CN      CH(CH.sub.3)CO.sub.2 CH.sub.3                                                             135-138                                   ______________________________________                                    

USE EXAMPLES

The herbicidal action of the N-aryltetrahydrophthalimide derivatives ofthe general formula Ic on the growth of test plants was illustrated bythe following greenhouse experiments.

The vessels employed were plastic flowerpots having a volume of 300 cm³,and which were filled with a sandy loam containing about 3.0% humus. Theseeds of the test plants were sown shallow, and separately, according tospecies.

For the preemergence treatment, the active ingredients were applied tothe surface of the soil immediately after the seeds had been sown. Thecompounds were emulsified or suspended in water as vehicle, and sprayedthrough finely distributing nozzles. The application rate was 3.0 kg/ha.After the agents had been applied, the vessels were lightlysprinkler-irrigated to induce germination and growth. Transparentplastic covers were then placed on the vessels until the plants hadtaken root. The cover ensured uniform germination of the plants, insofaras this was not impaired by the active ingredients.

For the postemergence treatment, the test plants were grown to a heightof from 3 to 15 cm, depending on growth form, before being treated. Forthis treatment, either plants which had been sown directly in the potsand grown there were selected, or plants which had been grown fromseedlings and transplanted to the vessels a few days before treatment.The application rates for postemergence treatment varied from ingredientto ingredient and were from 0.03 to 0.06 kg/ha. No covers were placed onthe vessels in this treatment method.

The pots were set up in the greenhouse--species from warmer areas atfrom 20° to 36° C., and species from moderate climates at 10° to 20° C.The experiments were run for 2 to 4 weeks. During this period the plantswere tended and their reactions to the various treatments assessed.

The plants used for the greenhouse experiments were Abutilontheophrasti, Amaranthus retroflexus, Arachis hypogaea, Avena sativa,Chenopodium album, chrysanthemum coronarium, Echinochloa crus-galli,Galium aparine, Ipomoea spp., Lamium amplexicaule, Lolium multiflorum,Mercurialis annua, Polygonum aviculare, Solanum nigrum, Stellaria media,and Triticum aestivum.

On preemergence application, compounds nos. 1c and 2c (applied at a rateof 3 kg/ha) proved to be suitable for combating monocotyledonous weeds.Oats, for example, were hardly affected, if at all.

Postemergence, compounds nos. 3c and 4c proved to have a strongherbicidal action on dicotyledonous unwanted plants at a rate of 0.06kg/ha. They also proved selective in groundnuts, which suffered noappreciable damage.

Compound 9c, at a rate of 0.03 kg/ha, proved to be suitable forcombating a broad spectrum of unwanted plants; wheat, as an example of acrop plant, suffered hardly any damage. This compound is therefore aselective herbicidal active ingredient.

By comparison with prior art active ingredient A from GB-A-2,150,929##STR17## compound no. 5c exhibited a considerably stronger herbicidalaction ona number of unwanted plants.

We claim:
 1. An N-aryltetrahydrophthalimide of the formula ##STR18##where R¹ and R² are each hydrogen and R³ and C₁ -C₃ -alkyl which issubstituted by C₃ -C₈ -alkenyloxycarbonyl, by C₃ -C₈ -alkynyloxycarbonylor by C₂ -C₁₀ -alkoxycarbonyl, which may be substituted in the alkoxymoiety by C₁ -C₄ -alkoxy, halogen or phenyl.
 2. A compound of theformula Ic as defined in claim 1, wherein R³ is CH(CH₃)CO₂ CH₃.
 3. Acompound of the formula Ic as defined in claim 1, wherein R³ is CH₂ CO₂CH₃.
 4. A herbicidal composition which comprises: a carrier and/ordiluent and an effective amount of a compound of the formula Ic asdefined in claim
 1. 5. A process for controlling the growth of unwantedplants which comprises: applying to the unwanted plants or their habitata herbicidally effective amount of a compound Ic as defined in claim 1.